Switzerland's failed to give us a formal response to our proposed mutual defense pact which would ultimately benefit them. We're being trash talked on their Wiki and in addition to that, many people have pointed out that as soon as the treaty ends they'll just break off from the Catholic Church. So I ask why should we even help them?
Great Britain is already at war with Switzerland. Why should we get into yet another war for the sake of a nation that spits on our glorious name and then comes crying to us for help.
Switzerland has no army what so ever. We can take Tuscany and Hesse just as easily through war as we could through diplomacy, and on the bright side, we won't be having to get into another war with GB to do it. It's only logical.